The display screen on a mobile electronic handheld device may be adjusted for different operating environments. For handheld devices having a display whose operation may be enhanced via backlighting (e.g. a Liquid Crystal Display (LCD)), the backlight should be very bright in outdoor or sunlight conditions for the display to be readable, whereas in normal indoor or office conditions, the backlight should operate at medium brightness and in dim or dark conditions, the backlight should be at low intensity so as to avoid eye strain.
Arrangements have been implemented in GPS displays and laptop computers for providing basic automatic screen and keypad backlighting adjustment, and for providing backlight adjustment of a display in mobile electronic handheld devices, such as disclosed in co-pending U.S. patent application Ser. No. 11/261,708, filed Oct. 31, 2005, and entitled AUTOMATIC SCREEN AND KEYPAD BRIGHTNESS ADJUSTMENT ON A MOBILE HANDHELD ELECTRONIC DEVICE.
Mobile electronic handheld devices conventionally include a light sensor for sampling ambient light conditions, on the basis of which display backlighting may be adjusted for readability in different operating environments (e.g. dimly lit environments, normal indoor environments and bright environments), for example as set forth in U.S. Pat. No. 7,352,930, entitled SHARED LIGHT PIPE FOR A MESSAGE INDICATOR AND LIGHT SENSOR. The location of such light sensors on the device may be such that the sensor becomes covered, and therefore unreliable, in some circumstances. For example, in handheld devices with displays that operate in multiple orientations of the device (e.g. portrait mode and landscape mode), and which have a sensor disposed at a location on the device where a user may be inclined to grip the device in one of the orientations (e.g. landscape mode), it is possible that the user's finger(s) or thumb(s) may inadvertently cover and thereby block the light sensor. A mobile electronic device, and a method that can be carried out by the mobile electronic device, will be described below that may advantageously control display backlight operation so as to accommodate the possibility that the sensor may be blocked in certain orientations of the device.